#developer_provider_name ⇒ String

The "domain" by which Cognito will refer to your users. This name
acts as a placeholder that allows your backend and the Cognito
service to communicate about the developer provider. For the
DeveloperProviderName, you can use letters as well as period
(.), underscore (_), and dash (-).

Once you have set a developer provider name, you cannot change it.
Please take care in setting this parameter.